Structure-toxicity relationships for three mechanisms of action of toxicity to Vibrio fischeri.

Quantitative structure-activity relationships (QSARs) have been developed with the logarithm of the inverse of 15-min toxicity (pT15) to Vibrio fischeri (the acute Microtox test). Statistically, robust QSARs were found for alkanones acting by the nonreactive, baseline narcosis mechanism of action [pT15 = 0.99 (log Kow)-2.08, n = 6, s = 0.24, r2 = 0.988, F = 405]; aldehydes acting by the Schiff base-forming mechanism of electrophilicity [pT15 = 0.55(log Kow)-0.58, n = 6, s = 0.07, r2 = 0.994, F = 782]; and alkenals acting by the Michael-type acceptor mechanism of electrophilicity [pT15 = 0.52(log Kow) + 0.35, n = 6, s = 0.19, r2 = 0.914, F = 54.5]. Efforts to model toxicity across mechanism of action resulted in the development of a response surface [pT15 = 0.79(log Kow)-1.17 (ELUMO)-0.41, n = 19, s = 0.46, r2 = 0.892, F = 75.3]. In addition, an excellent correlation was found between Tetrahymena pyriformis [log(1/IGC50)] and V. fischeri. [log(1/IGC50) = 0.86(pT15)-0.25, n = 19, s = 0.25, r2 = 0.957, F = 405] toxicity.